The VUB (Programming Technology Lab, System and Software Engineering
Lab), ULB (deComp) and the Belgian Association for Dynamic Languages
(BADL) are very pleased to invite you to a whole day of presentations
about the programming languages Self, Smalltalk and Common Lisp by
experts in these languages. Besides some introductory material for each
language, the reflective facilities in the respective programming
environments will be highlighted. The presentations will be especially
interesting for people with good knowledge about current mainstream
object-oriented languages like Java, C# and C++ who want to get a deeper
understanding about the expressive power of Self, Smalltalk and Common
Lisp. In order to prepare the ground for these presentations, Professor
Viviane Jonckers will introduce the day by an overview of the benefits
of teaching dynamic languages to undergraduate students in computer
science. She will especially discuss the specific advantages of using
Scheme as an introductory language instead of the more widely employed
Java language.

Attendance is free and open to the public. Please make sure to register
for the event by sending an e-mail to Pascal Costanza
(pascal.costanza@vub.ac.be), so we can plan ahead. The number of places
will be limited according to the exact location of the event and will be
allocated on a first-come, first-serve basis. Watch the website for the
exact schedule, location and any news athttp://prog.vub.ac.be/events/2005/BADL/DLD/dld.html.

The VUB has a rich history in dynamic programming language teaching and
research. Ever since the late 80’s, compulsory courses on Lisp and
Smalltalk have played an important role in the last two years of the
computer science curriculum. Since the early 90’s, this role was further
intensified by selecting Scheme as the introductory course in the first
year and by promoting Scheme as the lingua franca for most courses in
the first two years. Professor Jonckers’ introductory talk to the
dynamic languages day explains how this early exposure to the dynamic
paradigm is the seed that gives students the skills to fully grasp and
appreciate the more advanced dynamic paradigms (such as Lisp, CLOS,
Smalltalk and Self) in subsequent courses of their computer science
training.

Self (Ellen Van Paesschen)
~~~~~~~~~~~~~~~~~~~~~~~~~~

Self is a prototype-based object-oriented programming language where
everything is an object and all manipulation of objects is initiated
through message sending. A prototype-based language eschews classes and
allows object creation ex-nihilo or by cloning prototypes. Self
resembles Smalltalk in both its syntax and semantics. Other
characteristics of Self are delegation (object-centered inheritance),
parent sharing and child sharing (multiple inheritance), and dynamic
parent modification. Further the Self environment includes a powerful
mechanism for reflective meta-programming based on mirror objects. The
Self group were also the first to introduce traits objects that gather
shared and reusable behavior between objects in order to program in a
more efficient and structured way.

After a brief introduction to the highly interactive Self environment
the language’s basics and its syntax and semantics are presented. Next
the most important advanced features such as mirrors and dynamic parent
modification are illustrated.

Smalltalk is class-based object-oriented programming language.
Everything in Smalltalk is an object and these objects communicate
through messages. The Smalltalk language itself offers only very few
programming constructs and is thus easy to learn and grasp. Therefore,
the expressive power of Smalltalk lies in its huge library of
frameworks, which includes an extensive metaobject protocol that enables
powerful dynamic (runtime) reflection. Furthermore, perhaps one of the
most significant advantages of Smalltalk outside of the language itself
is that software development is a truly dynamic experience. The
Smalltalk environment features the incremental development of an
application where there is no strict separation between development and
execution cycles, leading to an interactive and dynamic development process.

Besides a short introduction to the Smalltalk programming language, this
presentation will focus on the dynamic reflective facilities of
Smalltalk. We will demonstrate the power of its metaobject protocol
through a number of tools that extensively rely on it. Furthermore, we
will provide some insight in the dynamic nature of Smalltalk development
through a live demonstration.

* In most OOP languages, methods belong to classes and are invoked by
sending messages. In CLOS, methods belong to generic functions instead
of classes, and those generic functions select and execute the correct
method according to the types of the arguments they receive.

* The CLOS Metaobject Protocol (MOP) specifies how its essential
building blocks are to be implemented in CLOS itself. This allows
extending its object model with metaclasses that change important
aspects of CLOS for a well-defined scope.

This presentation introduces these two notions. The code for an
interpreter for generic functions that performs selection and execution
of methods will be developed live during the presentation. This will be
followed by a discussion how that code can be extended to introduce, for
example, multimethods and AOP-style advices, and a sketch how generic
functions are implemented efficiently in the “real” world. In the second
part, the extensibility of the CLOS MOP will be illustrated by
implementing – live – the (hashtable-based) Python object model as a
metaclass. Other practical extensions based on the CLOS MOP are also
sketched, like object-relational mappings, interfaces to
foreign-language objects, and domain-specific annotations in classes.

Biographies
~~~~~~~~~~~

Viviane Jonckers received a master degree in Computer Science from the
Vrije Universiteit Brussel in 1983 and a Ph.D. degree in Sciences from
the same university in 1987. Since 1987 she is a professor both in the
Computer Science Department of the faculty of Sciences as in the
Computer Science group of the Engineering Faculty. Currently, she is the
director of the System and Software Engineering Lab. Her current
research interests are in integrated software development methods with a
focus on component based software development and aspect oriented
software development. She participated in and has been project manager
of several national and international R&D projects.

Roel Wuyts is professor at the University Libre de Bruxelles, where he
leads the deComp group. His fields of interest are logic meta
programming, forms of reflection and language design. On the side he
also dabbles in development environments. Quite a lot his development is
done in Smalltalk, extensively using the reflective facilities in that
language to do research in language symbiosis, development environments
and for rapid programming in gneral. From the moment he realized that
dynamicity was what he really liked in all of his favourite programming
languages (Smalltalk, Prolog and Scheme), he has been trying to grow the
dynamic languages field again. Part of this endavour was the
organization of the first Dynamic Language Symposium, a symposium
co-organized with OOPSLA’2005 in San Diego.

Johan Brichau currently holds a postdoc position at the Laboratoire
d’Informatique Fondamentale de Lille (LIFL). He is also associated with
the Programming Technology Lab at the Vrije Universiteit Brussel, where
he obtained a Ph.D. degree in Computer Sciences in 2005. Johan’s
research is focusing on the use of metaprogramming in the context of
generative programming techniques and aspect-oriented programming
languages. To this extent, he has been extensively using the Smalltalk
metaobject protocol for the creation and development of (generative)
logic metaprogramming techniques as well as aspect-oriented language
extensions to Smalltalk.

Pascal Costanza has a Ph.D. degree from the University of Bonn, Germany.
His past involvements include specification and implementation of the
languages Gilgul and Lava, and the design and application of the
JMangler framework for load-time transformation of Java class files. He
has also implemented ContextL, the first programming language extension
for Context-oriented Programming based on CLOS, and aspect-oriented
extensions for CLOS, which all heavily rely on the CLOS MOP. He is
furthermore the initiator and lead of Closer, an open source project
that provides a compatibility layer for the CLOS MOP across multiple
Common Lisp implementations.

Ellen Van Paesschen obtained a master degree in computer science at the
Vrije Universiteit Brussel in 2000. Currently she is a Ph.D. student at
the Programming Technology Lab. Ellen’s research is focusing on using
dynamic and prototype-based languages for model-driven development and
round-trip engineering (RTE). She has created a research prototype of a
dynamic prototype-based RTE environment in Self which is the main
implementation language in her research. This environment differs from
other existing tools at the level of synchronisation, run-time objects
and constraint enforcement steered from an analysis model. Her other
interests include (the analysis phase during) software engineering and
role modelling.